Every day, 9,000 children and numerous adults die after consuming contaminated water. Over half of all hospital beds in impacted regions are filled by people suffering from diseases caused by water that is contaminated with bacteria. Natural disasters that occur every year prompt organizations like the “UN” and “Doctors Without Borders” to invest millions of Euros in short-term supplies of drinking water to impacted countries. In addition to the human suffering, the economic damage and the disadvantages to the entire healthcare system are enormous. The “United Nations” has acknowledged the problem and in response has declared its “Millennium Development Goals”. As part of these goals, all member countries have pledged to provide one-half of the worldwide population suffering from a lack of clean drinking water with an adequate drinking water supply by the year 2015. This means that every year, 125 million people will have to be provided with a long-term and sustainable supply of water. The countries of the “UN” have provided 11.3 billion dollars per year to accomplish this goal. In order to put these funds to meaningful use, the “UN” and the organizations and countries involved with the project are seeking solutions in the field of drinking water disinfection that are cost-efficient and can be easily implemented.
Already established is “solar drinking water disinfection” (SODIS). SODIS was developed by ETH Zurich, and has been characterized by the “WHO” and the “UN” as the most efficient and cost-effective method of drinking water disinfection”. Internationally, SODIS can already claim 3 million users; however, there are some disadvantages in its application and its acceptance. Currently, the recommended value for the solar disinfection of drinking water is 6 hours of direct sunlight and 12-18 hours under partly cloudy conditions. Naturally, these specifications are dependent upon various factors, such as the position of the sun, the degree of cloudiness, the temperature, shadowing, wind and precipitation, which complicate the estimation of the amount of sunlight that is required and impair confidence in the actual degree of disinfection. Due to the lack of control of the method, the water frequently is not exposed long enough to the sun, resulting in incomplete disinfection. This, in turn, results in the users becoming infected with dysentery, cholera, typhus, etc.
The problem addressed by the invention is that of devising a reliable and easily implemented option for detecting the disinfection of a liquid, particularly of drinking water.